This invention relates generally to heat sinks for use on a printed circuit (PC) board and is particularly directed to a two piece heat sink which provides a large surface area per unit volume and thus efficient heat tranfer/dissipation and requires minimal PC board surface for mounting.
Heat sinks are typically comprised of a metal having a high thermal conductivity and are mounted upon a PC board for limiting the operating temperature of electronic components positioned in circuit upon the board. Ideally, the heat sink should occupy a minimum area on the PC board to permit high density electronic component packaging. The heat sink should also provide a high degree of heat transfer and thermal dissipation to accommodate the increased density of the electronic circuitry associated therewith. Increasing the thermal dissipation by means of convection generally requires increasing the surface area per unit volume of the heat sink.
In the past, attempts to increase the heat sink surface area per unit volume have resulted in corresponding increases in the area upon the PC board occupied by the heat sink. Approaches to minimizing PC board mounting area while increasing heat sink surface area have generally resulted in finned structures wherein a plurality of planar fins are oriented generally parallel to the surface of the PC board. This fin orientation provides only limited thermal dissipation by convection since the heated air rises generally perpendicular to the surface of the PC board and only the outer edges of the fins are exposed to the upward air flow producing only limited convection cooling. Attempts to orient the fins generally perpendicular to the surface of the PC board and thus increase the air flow over the fins have resulted in heat sink arrangements which require considerable PC board mounting area or which involve the coupling of various heat sink components in forming the heat sink structure. The manner in which these heat sink components are coupled typically involves the use of screws or nut/bolt combinations or the soldering of adjoining heat sink components. In either case, heat transfer between abutting heat sink components is limited by such coupling arrangements and thermal dissipation is correspondingly inhibited.
The present invention overcomes the aforementioned limitations of the prior art by providing a two piece heat sink assembly which requires minimal PC board mounting area, affords a high degree of heat transfer between the two heat sink components, provides a finned structure offering maximum heat sink surface area per unit volume, and includes fins oriented along the direction of heated air flow.